GBS analysis of Orobanche crenata populations in Algeria supports local
adaptation and host-specialization
Abstract
Crenate broomrape (Orobanche crenata Forsk.) is a serious long-standing
parasitic weed problem in Algeria, mainly affecting legumes but also
vegetable crops. Unresolved questions for parasitic weeds revolve around
the extent to which these plants undergo local adaptation, especially
with respect to host specialization, which would be expected to be a
strong selective factor for obligate parasitic plants. In the present
study, the Genotyping-By-Sequencing (GBS) approach was used to analyze
genetic diversity and population structure of 10 Algerian O. crenata
populations with different geographical origins and host species (faba
bean, pea, chickpea, carrot and tomato). In total, 8,004 high-quality
single-nucleotide polymorphisms were obtained and used across the study.
Genetic diversity and relationships of 95 individuals from 10
populations were studied using model-based ancestry analysis, principal
components analysis, discriminant analysis of principal components, and
phylogeny approaches. The genetic differentiation (FST) between pairs of
populations was lower between adjacent populations and higher between
geographically separated ones, but no support was found for isolation by
distance. Further analyses identified four genetic clusters and revealed
evidence of structuring among populations and hosts with more evident
structuring among hosts than strictly along a geographic gradient. In
the most striking example, O. crenata growing on pea had a distinct SNP
profile from those growing on faba bean or other crops. These results
illustrate the potential of GBS to reveal the dynamics of parasitic weed
dispersal and adaptation.